The present invention relates to the field of electrosurgery, and more particularly to methods for ablating, cauterizing and/or coagulating body tissue using radio frequency energy.
Radio frequency ablation is a method by which body tissue is destroyed by passing radio frequency current into the tissue. Some RF ablation procedures rely on application of high currents and low voltages to the body tissue, resulting in resistive heating of the tissue which ultimately destroys the tissue. These techniques suffer from the drawback that the heat generated at the tissue can penetrate deeply, making the depth of ablation difficult to predict and control. This procedure is thus disadvantageous in applications in which only a fine layer of tissue is to be ablated, or in areas of the body such as the heart or near the spinal cord where resistive heating can result in undesirable collateral damage to critical tissues and/or organs.
It is thus desirable to ablate such sensitive areas using high voltages and low currents, thus minimizing the amount of current applied to body tissue.
The present invention is a method and apparatus for treating tissue using an electrosurgical system. The system includes an electrosurgical system having an RF generator, a treatment electrode electrically coupled to the RF generator and positioned in contact with target tissue lo be treated, and a spark gap switch positioned between the RF generator and the target tissue. The spark gap includes a threshold voltage and is configured to prevent conduction of current from the RF generator to the tissue until the voltage across the spark gap reaches the threshold voltage.
A method according to the present invention includes the steps of using the RF generator to apply a voltage across the spark gap switch, the spark gap switch causing conduction of current from the RF generator to the target tissue once the voltage across the spark gap reaches the threshold voltage.